无人系统与自主计算实验室

Aerial Applications

Introduction

We present systematic solutions to some aerial applications with the integration of our algorithmic researches, including state estimation, onboard mapping, optimal trajectory generation and robust control. Here we introduce the aerial agile tracking as an instance.

In Fast-Tracker,  we propose a systematic solution that uses an unmanned aerial vehicle (UAV) to aggressively and safely track an agile target. The solution properly handles the challenging situations where the intent of the target and the dense environments are unknown to the UAV. Our work is divided into two parts: target motion prediction and tracking trajectory planning. In the target motion prediction method, we adopt polynomial regression based on the past target observations. Especially, Bernstein basis polynomial is used to enforce dynamical constraints in the regression method. The generated trajectory is extrapolated as the prediction of target future motion.

In the tracking trajectory planner, we design a heuristic function for the kinodynamic searching method that considers both the current target observation and motion prediction. Afterwards, a flight corridor that consists of a sequence of connected free-space 3-D grids is formed based on the results of the path searching. The back-end optimizer then generates a spatial-temporal optimal safe trajectory within the flight corridor. What’s more, due to the occlusion of obstacles, the limited sensing range, and the uncertainty of the target’s intent, it is hard for the UAV always to locate the target. We design a strategy so that the UAV can re-locate the target as soon as possible. The proposed solution is integrated into an onboard quadrotor system with a multi-camera set-up to robustify its sensing capability. We fully test the system in challenging real-world tracking missions to validate that our quadrotor can aggressively and safely track the target. Moreover, benchmark comparisons validate that the proposed method surpasses the cutting-edge methods on time efficiency and tracking effectiveness.

Related Research:

Fast-Tracker: A Robust Aerial System for Tracking Agile Target in Cluttered Environments, Zhichao Han, Ruibin Zhang, Neng Pan, Chao Xu, Fei Gao, the International Conference on Robotics and Automation (ICRA 2021). [paper] [code]